In many vacuum processing systems, for example those used in the semiconductor manufacturing industry, a dielectric or ceramic window is employed in the wall of a vacuum chamber to provide transparency for the coupling of RF energy through the wall and into the chamber to support a plasma within the chamber. In many deposition systems, including ionized physical vapor deposition (iPVD) systems, and in some etch systems, metal vapor that is present in the chamber has a tendency to form an electrically conductive film on the inside of the window. The film allows electrical currents to be induced that heat the window, which in many cases causes the window to fail. Catastrophic failure of the dielectric window in some cases can result in loss of an expensive substrate, and in all cases results in costly maintenance and non-productive down-time of the processing equipment.
Better analysis of the causes of such failures and the better prevention of such failures are needed.